An international research team, led by the British Antarctic Survey (BAS), is conducting studies in Antarctica to understand how glacier calving generates underwater tsunamis and their subsequent impact on ocean mixing. This phenomenon, which was observed by chance during a previous expedition, is now being actively investigated to determine its role in redistributing heat, oxygen, and nutrients in polar oceans, as well as its potential consequences for the Antarctic Ice Sheet and global climate systems.
Introduction to the Phenomenon
An international research team, led by the British Antarctic Survey (BAS), is currently investigating the process by which glacier calving in Antarctica generates underwater tsunamis. This research is taking place at the Antarctic's Rothera Research Station and aboard the UK's polar research ship RRS Sir David Attenborough. Glacier calving occurs when icebergs detach from glacier fronts and enter the ocean. These events create powerful submerged waves, often several meters high, that result in substantial ocean mixing.
Discovery and Initial Observations
The phenomenon of underwater tsunamis from glacier calving was first observed by chance during a previous BAS expedition to Antarctica aboard the RRS James Clark Ross. This expedition was led by Professor James Scourse from the University of Exeter. During this observation, ocean data was collected before, during, and after a calving event, providing initial insights into the process.
Mechanism and Oceanographic Impact
Ocean mixing involves the churning of different water depths, which facilitates the distribution of heat, oxygen, and nutrients. This process is considered essential for marine life and regional climate regulation. Historically, ocean mixing has been primarily attributed to factors such as wind, tides, and surface heat loss. However, initial findings from the current research suggest that underwater tsunamis play a substantial role in this process within polar oceans. Their impact on ocean mixing is noted to be comparable to wind-driven mixing in specific areas and has been observed to exceed the effect of tides in redistributing ocean heat.
Current Research Objectives and Methodology
Researchers are engaged in field work to characterize both calving events and the tsunamis they generate. Professor Michael Meredith, an oceanographer at BAS and the lead researcher, aims to understand the creation, function, and overall impact of these tsunamis. This includes examining how varying types of calving and seasonal conditions influence tsunami formation and how the resulting mixing affects polar climate and ecosystems.
Professor Katy Sheen, an oceanographer at Exeter and co-lead for a segment of the project, is focusing on the connection between glacial calving and the generation of internal tsunamis. The research employs a range of advanced technologies for data collection:
- Calving Monitoring: Remote cameras and underwater microphones are utilized to monitor calving events.
- Tsunami Measurement: Unmanned underwater vehicles, moored instruments, and water sampling are used to measure the generated tsunamis and their effects on local ocean chemistry and biology.
- Specific Glacier Study: Dr. Alexander Brearley, a BAS oceanographer, is deploying an autonomous underwater vehicle at Rothera Research Station to study the Sheldon Glacier.
The team is deploying advanced air, land-based, and ocean technologies to document individual glacier calving events and their tsunami impacts with high resolution.
Broader Implications
The underwater tsunamis and the ocean mixing they induce have potential consequences for the Southern Ocean and globally. Increased ocean mixing could draw warmer water from deeper layers towards the surface, potentially accelerating the melting of the Antarctic Ice Sheet and contributing to global sea level rise. Furthermore, this mixing has the potential to alter the distribution of nutrients, which could impact phytoplankton growth and, consequently, the broader ocean food chain. Professor Kate Hendry, a chemical oceanographer at BAS, highlights the interconnectedness of Antarctica's ice, ocean, and atmosphere in influencing global phenomena like sea levels and weather patterns. Future research is planned to investigate whether a warming climate might lead to an increase in the frequency and intensity of calving and tsunami events. Understanding this phenomenon is expected to enhance ocean models used for climate change predictions.
Collaborating Institutions
The POLOMINTS project represents a collaborative effort led by the British Antarctic Survey, involving several institutions:
- Scottish Association for Marine Science
- University of Southampton
- University of Leeds
- National Oceanography Centre
- University of Exeter
- Bangor University
- Scripps Institution of Oceanography (USA)
- Institute of Geophysics of the Polish Academy of Sciences (Poland)
- University of Delaware (USA)
- Rutgers University (USA)